Nancy, the girl told me another name for this is "swamp cancer".
When I was told about it, this dog is under a year old, had a mass on her, they found after the dog kept vomiting/diarhea, and couldn't get it under control..The mass was removed, but the dog didn't get better, so they did further testing and consulting (since there are supposedly no other cases of it here in CT) and came up positive for this.
The dog lives in a suburban neighborhood, with a pond behind their house, since the dog has been in the pond, they are suspect of that pond
Apparently, there is nothing more that can be done for this puppy, the mass is already growing back and will end up cutting off her airways
When I read the website and they said GSD's were high on the list,,just WOW!
My dog swims ALOT but I won't be letting her near any 'ponds' that's for sure